1. Field of the Invention
This invention relates generally to apparatus for condensing a vaporized fluid and more specifically to the use of such an apparatus in a solar energy converter.
2. Description of the Prior Art
Most apparatus providing a source of mechanical or electrical power rely upon some source of heat energy. This heat energy typically results from the combustion of fuels such as oil, gas, coal and gasoline. In some systems, nuclear materials have undergone fission to provide the heat energy.
The heat provided by these sources of energy has been converted into either electricity or mechanical work, unfortunately with tremendous inefficiency. The inefficiency has occurred as a result of the loss from the system of a very large portion of the heat provided by the source of energy. This lost heat has not been available for conversion into either electrical or mechanical work. By way of example it will be noted that internal combustion engines typically have an efficiency of 22%, diesel engines have an efficiency of approximately 40%, and nuclear or conventional power stations have an efficiency of approximately 50%.
Electrical power stations are typical of those sources of power which rely upon a source of heat energy. In these power stations, the heat is used to vaporize a working fluid, such as water, to provide steam having a high temperature and pressure. The steam is introduced to an expander, such as a stream engine or turbine, wherein the steam expands initially at substantially constant temperature, and subsequently at substantially constant entropy. This expansion provides mechanical work and additionally reduces the temperature and pressure of the steam.
In order to pump the working fluid back to the heat source, the exhaust steam is introduced into a condenser where it is cooled to a liquid state. This condensation is typically accomplished with vast condensing towers or the use of a relatively cold condensing medium. The condensing medium has typically included water which has been provided by a source such as a lake, river or ocean. After passing through the condenser, the heated condensing medium has been returned to the cooling source. It can be appreciated that this heat absorbed by the condensing medium has been lost as far as its conversion to power is concerned. Particularly disturbing has been the fact that as much energy has been lost in heating the condensing medium as has been provided by the engine or turbine in the form of electrical or mechanical power.
Some energy converters have relied upon solar radiation to heat the working fluid. Solar radiation is a preferred source of energy for several reasons. First, the quantity of energy available is generally unlimited. Additionally, the solar energy is relatively powerful, providing approximately one horsepower per square yard of surface when the rays of the sun are received normal to the surface. Furthermore, solar radiation is "free" when it is available.
The questionable availability of solar radiation is perhaps the primary deficiency of such a solar energy converter. The sun cannot be relied upon to shine continuously upon any particular area of the earth. Of course during the nighttime no radiant energy is received from the sun, but even during the daytime a considerable portion of the solar radiation may be intercepted by clouds and haze. These factors have reduced the reliability of solar radiation as a source of heat.
To provide for these "rainy days" it has been desirable to store energy in some form. It is known that energy in an electrical form can be stored in batteries. However, the cost of batteries having a capacity sufficient to store a large amount of electrical energy has been prohibitive. Furthermore, batteries have had an internal resistance which gradually dissipates the stored energy. As a consequence, batteries have not been capable of storing electrical energy for significant periods of time.
It is known that the dissipation of heat energy from an object can be reduced if the object is thermally insulated. For example, hot fluids have been disposed in vacuum bottles to inhibit the transfer of heat from the enclosed fluid through the walls of the bottle. These vacuum bottles as well known to be ineffectual for extended periods of time. This would make such insulating means inapplicable to the present invention for the long term storage of thermal energy. Other insulating means such as that used to lag pipes would be similarly undesirable for storing heat energy over an extended period of time.